When should you change the gas rings? and what are the advantages of a vertical foregrip? is it useful only for fulll auto firing?

[url]http://www.ar15.com/forums/topic.html?b=3&f=19&t=172409&w=myTopicPop[/url]

And what about the gas rings part?  Me too lazy to search. (and no cable modem, my bandwith be narrow!)

[b]HOW TO CHECK GAS RINGS[/b]

1. Remove bolt from upper.
2. Remove firing pin and pivot pin.
3. Make sure bolt is firmly seated into the bolt carrier.
4. Grasp bolt by the locking lugs ONLY.
5. Pick up assembly only with one hand and only by the LOCKING LUGS.
6. If the bolt stays in the carrier your gas rings are GOOD. [:D]
  If the carrier falls to the floor and you are left with only the bolt in your hand, it is time to replace the gas rings. [:(]

This is not 100% but is what is taught in the Colt LE Armorers school. [(:)]
I have found it to be an excellent method when I tested it to known new rings and known heavily worn rings.

as an armorer and a gunsmith i have never had to replace any gas rings. with the exception of replacing lost ones(darn privates). i just swiched to a one piece ring that should give a lifetime of use. plus there are no gaps to align.
[url=http://www.brownells.com/aspx/NS/Store/ProductDetail.aspx?p=18722&title=AR-15+MCFARLAND?%20BOLT%20GAS%20RING]MCFARLAND GAS RING[/url]

As an LE Armorer I have had to replace a few gas rings. Mostly on older full auto M4's used by our SWAT team. These guns get shot a lot!!

I have seen one of our old M16A1's running just fine with only ONE standard gas ring. The operator did not know where the other two rings had gone. After a day at the range we broke the rifles down for cleaning and found the one ring.

And yes he did some extra PT for not having his shit together.

Stagering the rings is BS. Next time you guys go to the range line all the gaps up and try it. We have never been able to induce a malfunction this way. Same with using a 30 round mag as a mono pod.